Dynamic control of connections with dual-connectivity-capable devices

ABSTRACT

A mechanism for controlling operation of a first access node that supports operation according to a first radio access technology (RAT) but does not support dual-connectivity operation according to the first RAT and a second RAT. A system detects a high extent of occurrences of dual-connectivity-capable user equipment devices (UEs) being connected with the first access node when the dual-connectivity-capable UEs could instead connect with a second access node that supports the dual-connectivity operation. And in response, the first access node blocks dual-connectivity-capable UEs from being connected with the first access node while allowing UEs that are not dual-connectivity capable to be connected with the first access node.

BACKGROUND

A cellular wireless network typically includes a number of cell sitesincluding access nodes that are configured to provide wireless coverageareas in which user equipment devices (UEs) such as cell phones, tabletcomputers, machine-type-communication devices, tracking devices,embedded wireless modules, and/or other wirelessly equippedcommunication devices (whether or not user operated) can operate.Further, each access node could be coupled with a core network thatprovides connectivity with various application servers and/or transportnetworks, such as the public switched telephone network (PSTN) and/orthe Internet for instance. With this arrangement, a UE within coverageof the cellular network could engage in air interface communication withan access node and could thereby communicate via the access node withvarious application servers and other entities.

Such a network could operate in accordance with a particular radioaccess technology (RAT), with communications from the access nodes toUEs defining a downlink or forward link and communications from the UEsto the access nodes defining an uplink or reverse link.

Over the years, the industry has developed various generations of RATs,in a continuous effort to increase available data rate and quality ofservice for end users. These generations have ranged from “1G,” whichused simple analog frequency modulation to facilitate basic voice-callservice, to “4G”—such as Long Term Evolution (LTE), which nowfacilitates mobile broadband service using technologies such asorthogonal frequency division multiplexing (OFDM) and multiple inputmultiple output (MIMO). And most recently, the industry is now exploringdevelopments in “5G” and particularly “5G NR” (5G New Radio), which mayuse a scalable OFDM air interface, advanced channel coding, massiveMIMO, beamforming, and/or other features, to support higher data ratesand countless applications, such as mission-critical services, enhancedmobile broadband, and massive Internet of Things (IoT).

In accordance with the RAT, each coverage area could operate on one ormore carriers, each of which could be frequency division duplex (FDD),defining separate frequency channels for downlink and uplinkcommunication, or time division duplex (TDD), with a single frequencychannel multiplexed over time between downlink and uplink use. Further,on the downlink and uplink, each carrier could be structured to definevarious physical channels including time-frequency resources forcarrying information between the access node and UEs. For example, theair interface could be divided over time into frames, each divided inturn into subframes and timeslots, and the carrier bandwidth (frequencywidth of the carrier on the downlink and/or uplink) could be dividedover frequency into subcarriers, which could be grouped within eachtimeslot to define physical resource blocks (PRBs) in which thesubcarriers can be modulated to carry data.

OVERVIEW

When a UE enters into coverage of an example network, the UE coulddetect threshold strong coverage of an access node (e.g., a thresholdstrong reference signal broadcast by the access node) and could thenengage in random-access and Radio Resource Control (RRC) signaling toestablish an RRC connection through which the access node will thenserve the UE. Further, if the UE is not already registered for servicewith the core network, the UE could transmit to the access node anattach request, which the access node could forward to a core-networkcontroller for processing. And the core-network controller could thencoordinate setup for the UE of one or more user-plane bearers extendingbetween the UE and a core-network gateway that providestransport-network connectivity.

Once the UE is so connected and registered, the access node could thenserve the UE in a connected mode, managing downlink air-interfacecommunication of packet data to the UE and uplink air-interfacecommunication of packet data from the UE.

For example, when packet data for the UE arrives at the core networkfrom a transport network, the data could flow to the UE's serving accessnode, and the access node could then schedule and provide transmissionof that data to the UE on particular downlink PRBs. Likewise, when theUE has data to transmit on the transport network, the UE could transmita scheduling request to the access node, the access node couldresponsively schedule transmission of that data from the UE onparticular uplink PRBs, and the UE could accordingly transmit the datato the access node for forwarding through the core network to thetransport network.

Further, when a UE is served by an access node, the UE could monitorcoverage strength of the access node and of neighboring access nodes.And if and when the UE determines that certain defined coverage strengththresholds are met (such as neighboring coverage being thresholdstronger than serving coverage), the UE could signal to its servingaccess node, and the serving access node could then coordinate handoverof the UE to the neighboring access node.

As the industry advances from one generation of RAT to the next,networks and UEs may also be configured to support service on multipleRATs at once. With the transition from 4G LTE to 5G NR, for instance, awireless operator that provides cell sites with 4G access nodes (evolvedNode-Bs (eNBs)) could upgrade those cell sites to include 5G accessnodes (next generation Node-Bs (gNBs)) as well and to support anarrangement referred to as EUTRA-NR Dual Connectivity (EN-DC) in whichUEs could be served concurrently over a 4G connection and a 5Gconnection. Further, new UEs could likewise be configured with both 4Gradios and 5G radios and with logic to support EN-DC operation providedby such cell sites. This arrangement could help support transition from4G technology to 5G technology and could also facilitate higher peakdata rate of communication by allowing data to be multiplexed over 4Gand 5G connections, among possibly other benefits.

When a UE that supports EN-DC service enters into such a cell site, theUE could initially scan for and detect coverage of the cell site's 4GeNB and engage in random-access and RRC signaling to establish a 4Gconnection between the UE and the 4G eNB as discussed above. In turn,perhaps having determined from profile data that the UE is EN-DCcapable, the 4G eNB could then work with the core network and the 5G gNBto establish a 5G connection between the UE and the 5G gNB and toestablish bearer connectivity for the UE between the 5G gNB and the corenetwork. With these 4G and 5G connections so established, the 4G and 5Gaccess nodes could then serve the UE with packet-data communicationsconcurrently on their respective connections with the UE, with a portionof data flowing over the UE's 4G connection with the 4G eNB concurrentlywith another portion of the data flowing over the UE's 5G connectionwith the 5G eNB.

More generally, dual-connectivity service (or non-standalone service) ofa UE may involve the UE having co-existing connections according tomultiple different RATs and being served with communication concurrentlyon those multiple different-RAT connections, which might provide the UEwith increased peak data rate. This is to be distinguished fromsingle-connectivity service (or standalone service) of a UE, where theUE is served with communication according to just a single RAT, such aswith just a 4G connection or just a 5G connection for instance.

In some dual-connectivity arrangements, an access node operating under afirst RAT (i.e., a first-RAT access node) could serve as a master node(MN), responsible for RRC signaling with the UE, responsible forcoordinating setup and teardown of dual-connectivity service for the UE,and functioning as an anchor point for core-network control signalingrelated to the dual-connected UE. And an access node operating under asecond RAT (i.e., a second-RAT access node) could serve as a secondarynode (SN), to provide increased data capacity for the UE for instance.With EN-DC, for example, a 4G eNB could operate as the MN (referred toas an MeNB), and a 5G gNB could operate as the SN (referred to as anSgNB).

As a wireless operator upgrades its network from providing serviceaccording to a first RAT to additionally providing service according toa second RAT and providing dual-connectivity service on the two RATs,the operator may do so progressively from cell site to cell site. As aresult, at least during that transition but also possibly later, some ofthe network's first-RAT access nodes may support both providingfirst-RAT-only service and providing dual-connectivity service(dual-connectivity-capable first-RAT access nodes), while other of thenetwork's first-RAT access nodes may support providing justfirst-RAT-only service and not dual-connectivity service (first-RAT-onlyaccess nodes).

Further, the development of UEs that are configured to supportdual-connectivity service may also be progressive. Thus, for at leastsome time, some UEs may support engaging in first-RAT service andengaging in dual-connectivity service (dual-connectivity-capable UEs),while other UEs may support engaging in first-RAT service but notengaging in dual-connectivity service (first-RAT-only UEs).

For instance, when an operator upgrades its network to add 5G gNBs andto configure 4G eNBs to support EN-DC service through interworking withthe 5G gNBs, some of the network's 4G eNBs may support providing 4Gservice and also providing EN-DC service (EN-DC-capable 4G eNBs), whileother of the network's 4G eNBs may support providing just 4G service butmay not support providing EN-DC service (4G-only eNBs). Likewise, someUEs that subscribe to the operator's service may support engaging in 4Gservice and engaging in EN-DC service (EN-DC-capable UEs), while otherUEs that subscribe to the operator's service may support engaging in 4Gservice but may not support engaging in EN-DC service (4G-only UEs).

In this or similar situations, one technological problem that can ariseis that, if a first-RAT-only access node and a dual-connectivity-capablefirst-RAT access node provide overlapping coverage, at least somedual-connectivity-capable UEs that are within the coverage-overlap areamay end up connecting with the first-RAT-only access node rather thanwith the dual-connectivity-capable first-RAT access node and maytherefore not benefit from receiving dual-connectivity service. Thiscould happen during initial connection or through handover, for instanceif the UEs detect sufficiently stronger coverage from the first-RAT-onlyaccess node than from the dual-connectivity-capable first-RAT accessnode.

For instance, if an EN-DC-capable 4G eNB and a 4G-only eNB provideoverlapping coverage, at least some EN-DC-capable UEs that are withinthe coverage-overlap area may receive sufficiently stronger coveragefrom the 4G-only eNB than from the EN-DC-capable 4G eNB and maytherefore end up connecting with the 4G-only eNB rather than with theEN-DC-capable UE. As a result, those EN-DC capable UEs may not benefitfrom EN-DC service that they could otherwise be receiving. Further,having the 4G-only eNB serve those EN-DC-capable UEs could consumelimited resources (e.g., PRBs or processing resources) of the 4G-onlyeNB, which could limit the service that the 4G-only eNB could provide to4G-only UEs.

The present disclosure provides a mechanism to help address thisproblem. In accordance with the disclosure, a system will keep track ofoccurrences of dual-connectivity-capable UEs being connected with thefirst-RAT-only access node when the dual-connectivity-capable UEs arealso within sufficiently strong coverage of thedual-connectivity-capable first-RAT access node. Based on this tracking,the system will then detect a predefined threshold high extent of suchoccurrences. And in response, the system will blockdual-connectivity-capable UEs (i.e., one or more UEs of that class) frombeing connected with the first-RAT-only access node while allowingfirst-RAT-only UEs to be connected with the first-RAT-only access node.

Taking this action could help to increase the likelihood thatdual-connectivity-capable UEs will instead connect with (or hand overto) the dual-connectivity-capable first-RAT access node, so that thoseUEs can benefit from dual-connectivity service, and may also help tofree up resources of the first-RAT-only access node to servefirst-RAT-only UEs.

In an example implementation, the system could determine or predict thatsuch occurrences tend to occur at a particular time of day and, inresponse, could cause the first-RAT-only access node to blockdual-connectivity-capable UEs from being connected with the first-RATaccess node at or approaching that time of day. Alternatively, thesystem could do this without limitation to a particular time of day orthe like.

With 4G and EN-DC, for instance, such a system could keep track ofoccurrences of EN-DC-capable UEs being connected with a 4G-only eNB whenthose UEs are also within sufficiently strong coverage of one or moreEN-DC-capable 4G eNBs. Based on this tracking, the system could thendetect at least a predefined threshold high extent of such occurrences,possibly at a particular time of day. And in response, the system couldthen block EN-DC-capable UEs from being connected with the 4G-only eNBwhile allowing 4G-only UEs to be connected with the 4G-only eNB,possibly at or approaching the particular time of day, so as to helpincrease the likelihood that EN-DC-capable UEs will instead connect with(or hand over to) an EN-DC-capable 4G eNB.

Blocking dual-connectivity-capable UEs from being connected with thefirst-RAT-only access node while allowing first-RAT-only UEs to beconnected with the first-RAT-only access node could be carried out bythe first-RAT-only access node and/or an associated control entity.

By way of example, if the first-RAT-only access node normally operatesin a mode in which the first-RAT-only access node allows UEs to beconnected with the first-RAT-only access node regardless of whether theUEs are dual-connectivity capable, the first-RAT-only access node couldswitch to operate in a mode in which, based on a UE beingdual-connectivity capable, the first-RAT-only access node would blockthe UE from being connected with the first-RAT-only access node.Further, the first-RAT-only access node could carry out the blocking invarious ways, examples of which include (i) declining new connectionrequests from the dual-connectivity-capable UE, (ii) declining hand-inof the dual-connectivity-capable UE, and (ii) releasing and redirectingthe dual-connectivity-UE to perhaps connect instead with adual-connectivity-capable access node that provides the overlappingcoverage.

These as well as other aspects, advantages, and alternatives will becomeapparent to those reading the following description, with referencewhere appropriate to the accompanying drawings. Further, it should beunderstood that the discussion in this overview and elsewhere in thisdocument is provided by way of example only and that numerous variationsare possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of an example wirelesscommunication system in which various disclosed features can beimplemented.

FIG. 2 is a flow chart depicting an example method in accordance withthe present disclosure.

FIG. 3 is another flow chart depicting an example method in accordancewith the disclosure.

FIG. 4 is a simplified block diagram of an example system operable inaccordance with the disclosure.

FIG. 5 is a simplified block diagram of an example access node operablein accordance with the disclosure.

DETAILED DESCRIPTION

An example implementation will now be described in the context of 4GLTE, 5G NR, and EN-DC. It should be understood, however, that theprinciples disclosed herein could extend to apply with respect to otherscenarios as well, such as with respect to other RATs and otherdual-connectivity configurations. Further, it should be understood thatother variations from the specific arrangements and processes describedare possible. For instance, various described entities, connections,functions, and other elements could be added, omitted, distributed,re-located, re-ordered, combined, or changed in other ways.

As noted above, FIG. 1 is a simplified block diagram of an examplewireless communication system in which various disclosed features can beimplemented. In particular, the figure depicts a representativearrangement including an EN-DC-capable cell site 12 having anEN-DC-capable 4G eNB 14 and a 5G gNB 16, and a 4G-ony cell site 18having a 4G-only base station 20 and not having a 5G gNB. (Note thatthese example cell sites might also support one or more other RATs asidefrom these, such as one or more legacy RATs for instance. But the focusof the example discussion here will be just 4G and 5G.)

Each of these cell sites could be at a respective location within aregion, and the two example cell sites could be adjacent to each other(or one encompassing the other) such that a UE could be in overlappingcoverage of the two cell sites and might be able to hand over from onecell site to the other.

In addition, each access node could also take various forms. Forinstance, an access node could be a macro access node of the type thatwould typically include a tower mounted antenna structure for providinga broad range of coverage. Or an access node could be a small-cellaccess node, femtocell access node, relay access node, or other type ofaccess node that might have a smaller form factor with an antennastructure that provides a narrower range of coverage. Further, at cellsite 12, the 4G eNB 14 and 5G gNB 16 might share an antenna tower and/orother such structures or equipment. Other arrangements are possible aswell.

Access nodes 14, 16, and 20 are each shown coupled with an example corenetwork 22. Core network 22 could be an evolved packet core (EPC)network, a next generation core (NGC) network, or another network thatincludes components that may support an applicable RAT and provideconnectivity with at least one transport network 24, such as theInternet for instance. Further, in an alternative embodiment, accessnodes may be coupled with different core networks than each other.

In an example implementation as shown, the core network 22 includes aserving gateway (SGW) 26, a packet data network gateway (PGW) 28, amobility management entity (MME) 30, and a home subscriber server (HSS)32. Each access node could have an interface with the SGW, the SGW couldhave an interface with the PGW, and the PGW could provide connectivitywith the transport network. With this arrangement, the SGW and PGW couldcooperatively provide user-plane connectivity between each access nodeand the transport network, to enable a UE served by an access node toengage in communication on the transport network, and the MME couldoperate as a core-network controller, to carry out operations such ascoordinating UE attachment and setup of user-plane bearers. Further, theHSS 30 could store UE profile records, which could specifyservice-subscription plans, UE configurations, and/or UE capabilityinformation, such as whether a UE is EN-DC capable for instance.

As noted above, the air interface between each access node and UEswithin its coverage could be structured to define various air-interfaceresources.

By way of example, in the time domain, the air interface could define acontinuum of 10-millisecond (ms) frames, each divided into ten 1-mssubframes, and each subframe could be further divided into a number oftimeslots, each additionally divided into symbol time segments. And inthe frequency domain, the bandwidth of each carrier on which the accessnode operates could be divided into subcarriers with specifiedsubcarrier spacing on the order of 15 to 240 kHz. With this arrangement,the air interface on each carrier could define an array of resourceelements each occupying a subcarrier and spanning a symbol time segment,and the access node and UEs could communicate with each other throughmodulation of the subcarriers to carry data in those resource elements.Variations of this arrangement are possible as well.

Further, particular sets of resource elements on the air interface couldbe grouped together to define the PRBs discussed above. In an exampleimplementation, each PRB could span one timeslot in the time domain anda group of subcarriers in the frequency domain. Depending on the carrierbandwidth, the air interface could thus support a certain number of suchPRBs across the bandwidth of the carrier within each timeslot.

In addition, certain resource elements on the downlink and uplink couldbe reserved for particular control-channel or shared-channelcommunications.

For instance, on the downlink, certain resource elements per subframe(or per downlink subframe in TDD) could be generally reserved to definea downlink control region for carrying control signaling such asscheduling directives and acknowledgements from the access node to UEs.And other resource elements per subframe could be generally reserved todefine a shared channel in which PRBs could carry scheduled datacommunications from the access node to UEs. Further, certain resourceelements in particular downlink subframes could be reserved to carrysynchronization signals that UEs could detect as an indication of thepresence of coverage and to establish timing synchronization, and otherresource elements per downlink subframe could be reserved to carry areference signal that UEs could measure as a basis to determine coveragestrength and to provide channel estimates to facilitate precoding,beamforming, or the like.

On the uplink, on the other hand, certain resource elements per subframe(or per uplink subframe in TDD) could be reserved to define an uplinkcontrol region for carrying control signaling such as random-accessrequests, channel-quality reports, scheduling requests, andacknowledgements, from UEs to the access node. And other resourceelements per subframe could be reserved to define a shared channel inwhich PRBs could carry scheduled data communications from UEs to theaccess node. Further, still other resources on the uplink could bereserved for other purposes as well, such as for carrying uplinkreference signals or the like.

Note also that the 4G air interface and 4G service provided respectivelyby each 4G eNB 14, 20 could differ from the 5G air interface and 5Gservice provided by the 5G gNB 16 in various ways now known or laterdeveloped. For example, one may provide variable subcarrier spacing, butthe other may provide fixed subcarrier spacing. As another example, onemay have different symbol time segments than the other. As still anotherexample, one may make use of different MIMO technologies than the other.And as yet another example, with TDD carriers, one may have a flexibleTDD configuration and the other may have a fixed TDD configuration.Other examples are possible as well.

FIG. 1 further illustrates example UEs 34, 36 located within coverage ofcell site 12 and possibly also within coverage of cell site 14. Each ofthese UEs could take any of the forms noted above, among otherpossibilities, and the UEs could differ in form from each other.

UEs 34 are shown being EN-DC-capable UEs. As such, each UE 34 couldinclude a 4G radio for connecting with and being served by a 4G eNB, anda 5G radio for connecting with and being served by a 5G gNB. Further,each UE 34 could have logic and perhaps an associatedservice-subscription, enabling the UE to engage in EN-DC service whenavailable. Whereas UEs 36 are shown being 4G-only UEs. As such, each UE36 would include a 4G radio for connecting with and being served by a 4GeNB but may not include a 5G radio or may not include logic orservice-subscription support for engaging in EN-DC service.

Any such 4G-capable UE could initially scan for the presence of 4Gcoverage by searching for a broadcast synchronization signal on each ofone or more 4G carriers for instance. Upon finding 4G coverage from a 4GeNB, the UE could then determine coverage strength from the 4G eNB, suchas by evaluating reference signal receive strength (RSRP) or referencesignal receive quality (RSRQ), among other possibilities. And the UEcould determine if the coverage strength is sufficient to support aconnection, such as if the coverage strength is at least as high as apredefined threshold level deemed sufficiently strong to support aconnection. Upon determining that the coverage from the 4G eNB issufficiently strong, the UE could then engage in random-access signalingand RRC-configuration signaling with the 4G eNB to connect with the 4GeNB as noted above, thus putting the UE in an RRC-connected mode. Inparticular, the UE could transmit to the 4G eNB on an uplink physicalrandom access channel (PRACH) a random-access preamble, and the 4G eNBcould respond by assigning a temporary connection identifier to the UEand allocating uplink PRB resources for RRC signaling. The UE could thenuse the allocated uplink resources to transmit to the 4G eNB an RRCconnection request together with UE-identification information, and the4G eNB could grant the RRC connection request, thus establishing an RRCconnection between the 4G eNB and the UE.

In this process, the 4G eNB could require, as a condition precedent forallowing the UE to connect with the 4G eNB, that the UE be inthreshold-close signaling distance to the 4G eNB. The 4G eNB could checkfor this condition by determining a signal delay of the random-accesspreamble that the UE transmits to the 4G eNB (e.g., by comparing time ofarrival of the random-access preamble at the 4G eNB to a predefinedrandom-access transmission-time at which the UE would have transmittedthe random-access preamble), and determining if the signal delay is nohigher than a predefined maximum signal delay. If the 4G eNB determinesthat the signal delay is no higher than the predefined maximum signaldelay, then the 4G eNB could allow the UE to connect with the 4G eNB.Whereas, if the 4G eNB determines that the signal delay is higher thanthe predefined maximum signal delay, then the 4G eNB could block the UEfrom connecting, such as by disregarding the UE's random-access preambletransmission.

In any event, with at least an initial RRC connection established, theUE could then transmit to the 4G eNB an attach request message ifappropriate, which the 4G eNB could forward to the MME 30 forprocessing. And upon authenticating and authorizing the UE for service,the MME and 4G eNB could coordinate setup for the UE of at least oneuser-plane bearer. In particular, the MME could engage in signaling withthe 4G eNB and the SGW 26 to coordinate or trigger setup for the UE ofan access bearer, including an S1-U packet tunnel between the 4G eNB andthe SGW 26 and an S5 packet tunnel between the SGW 26 and the PGW 28.Further, the 4G eNB could engage in signaling with the UE to establish adata-radio bearer and other configuration parameters cooperativelydefining a 4G connection for the UE.

In relation to this attachment process, the 4G eNB could also receiveand store capability data for the UE, which could indicate variouscapabilities of the UE, such as whether or not the UE is EN-DC capablefor instance. By way of example, as a last step of the attachmentprocess, the 4G eNB could transmit to the UE an RRC message carrying aUE-capability enquiry, and the UE could respond to the 4G eNB with a “UEcapability information” information element (IE), which could indicateUE capabilities including whether the UE is EN-DC capable.Alternatively, the 4G eNB could receive this capabilities data from theHSS 32. The 4G eNB could then store this capability data in a contextrecord for the UE.

Once the UE is so connected with the 4G eNB, the 4G eNB could thenproceed to serve the UE in a standalone-4G mode in the manner discussedabove.

For instance, when data arrives at the 4G eNB for transmission to theUE, the 4G eNB could allocate one or more downlink PRBs in a subframefor use to transmit at least a portion of the data, defining a transportblock, to the UE. The 4G eNB could then transmit to the UE in thecontrol region of that subframe a Downlink Control Information (DCI)message that designates the PRBs, and the 4G eNB could accordinglytransmit the transport block to the UE in those designated PRBs.

And when the UE has data to transmit to the 4G eNB (e.g., fortransmission on the transport network), the UE could transmit to the 4GeNB a scheduling request that carries with it a buffer status report(BSR) indicating how much data the UE has buffered for transmission. Andin response, the 4G eNB could allocate one or more uplink PRBs in anupcoming subframe for carrying a transport block of that data from theUE and could transmit to the UE a DCI message that designates thoseupcoming PRBs. The UE could then accordingly transmit the transportblock to the 4G eNB in the designated PRBs.

If the 4G eNB that the UE connects with through the above process is theEN-DC-capable 4G eNB 14 and if the UE is an EN-DC capable UE 34, thenthe 4G eNB could additionally work to configure EN-DC service for the UE34.

For instance, the 4G eNB 14, operating as MeNB, could first engage inprocess to add the 5G gNB 16 as an SgNB for the UE 34, such as bytransmitting to the 5G gNB 16 an SgNB-Addition request to cause the 5GgNB to allocate resources for a 5G connection for the UE 34 on one ormore 5G carriers, receiving an SgNB-Addition-Request acknowledge messagefrom the 5G gNB 16, and engaging in associated RRC signaling with the UE34, in response to which the UE 34 could then access and completeestablishment of the 5G connection. Further, in certain implementations,the 4G eNB 14 could engage in signaling with the MME to trigger transferof the UE's access-bearer to the 5G gNB and could carry out one or moreother operations in relation to EN-DC setup for the UE 34.

The 4G eNB 14 and 5G gNB 16 could then provide the UE 34 with EN-DCservice, concurrently serving the UE 34 over their respectiveconnections with the UE 34. Namely, the 4G eNB 14 could allocate PRBs ofits 4G air interface as needed to carry data over the 4G connectionbetween the 4G eNB 14 and the UE 34, and the 5G gNB could allocate PRBsof its 5G air interface as needed to carry data over the 5G connectionbetween the 5G gNB 16 and the UE 34.

On the other hand, if the 4G eNB that the UE connects with through theabove process is the 4G-only eNB 20, then the 4G eNB would not configureEN-DC service for the UE, regardless of whether the UE's capability dataindicates that the UE is EN-DC capable. Consequently, if the UE is anEN-DC-capable UE 34, then the UE would not benefit from the EN-DCservice that it supports but would rather be restricted to engaging in4G-only service.

Unfortunately, however, this problem may tend to occur in a geographicarea where the 4G-only eNB 20 may provide stronger (e.g., sufficientlystronger) coverage than the EN-DC-capable 4G eNB 14 and whereEN-DC-capable UEs tend to operate. Namely, in that geographic area,there might be numerous occurrences of EN-DC-capable UEs finding thatcoverage from the 4G-only eNB 20 is sufficiently stronger than coveragefrom the EN-DC-capable 4G eNB 14 and therefore connecting with the4G-only eNB 20, and thus where those EN-DC-capable UEs do not benefitfrom the EN-DC service that they support and would also consumeresources of the 4G-only eNB 20 that might otherwise be available toserve 4G-only UEs.

As noted above, this problem could be addressed by a system detectingsuch a scenario and responsively blocking EN-DC-capable UEs from beingconnected with the 4G-only eNB 20 while allowing 4G-only UEs to beconnected with the 4G eNB 20. Such a system could be implemented as orby the 4G-only eNB 20, an element management system (EMS) 38 of the corenetwork, and/or one or more other entities. For instance, any suchentity or combination of entities might detect the scenario, and the4G-only eNB 20 might responsively block EN-DC-capable UEs from beingconnected with the 4G-only eNB 20 but still allow 4G-only UEs to beconnected with the 4G-only eNB 20.

In an example implementation, the system could keep track of instancesof EN-DC-capable UEs being connected with the 4G-only eNB 20. Forinstance, the 4G-only eNB 20 could identify such instances based on the4G-only eNB 20 being RRC connected with such UEs and learning fromcapability data or the like that the UEs are EN-DC capable, and the4G-only eNB 20 could record those instances and/or report the instancesto the EMS 38. Alternatively, the 4G-only eNB 20 could report to the EMSeach instance of a UE connecting with the 4G-only eNB 20, the EMS couldrefer to capabilities data to determine each such instance where the UEis EN-DC capable, and the EMS could record the instances.

Further, the system could identify such instances where theEN-DC-capable UEs that are connected with the 4G-only eNB 20 are alsolocated within a geographic area where the UEs may likely also havesufficiently strong coverage from the EN-DC-capable 4G eNB 14 (e.g.,strong enough coverage from the EN-DC-capable 4G eNB 14 that they couldhave connected instead with the EN-DC-capable 4G eNB 14.

The system could identify such instances in various ways. For instance,the system could determine the geographic location of each such UE,perhaps reported by the UEs during or after RRC connection, or throughuse of any other UE-location-determination process now known or laterdeveloped, and the system could compare those UE locations withpredefined data defining the geographic bounds of threshold strongcoverage of the EN-DC capable 4G eNB 14 to identify instances where theUEs are within those geographic bounds. Alternatively, some or all suchUEs might report to the 4G-only eNB 20 that the UEs are also withinsufficiently strong coverage of the EN-DC-capable 4G eNB 14. Further,the 4G-only eNB 20 could forward this or other such information to theEMS.

Based on this information, the system could thereby detect a thresholdhigh extent of such occurrences. For example, system could determinethat, of all UEs that connect with the 4G-only eNB 20, at least apredefined threshold high percentage of UEs are EN-DC-capable UEs thatcould instead connect with the EN-DC-capable 4G eNB 14. And as anotherexample, the system could detect at least a predefined threshold highfrequency (rate) of such instance per unit time. Further, the systemcould record the time of day of each such instance and could detect athreshold high extent of such occurrences at that time of day, such aswithin a given hour of day. And the system could detect these and/orother such high extent of occurrences repeatedly, such as over thecourse of multiple days or the like.

In response to detecting the threshold high extent of occurrences ofEN-DC-capable UEs being connected with the 4G-only eNB 20 when the UEscould instead connect with the EN-DC-capable 4G eNB 14, the system couldthen block EN-DC-capable UEs from being connected with the 4G-only eNB20, so as to help increase the likelihood that EN-DC-capable UEs willinstead connect with the EN-DC-capable 4G eNB. For instance, the 4G-onlyeNB 20 could responsively set itself to implement this blocking, and/orthe EMS could responsively signal to the 4G-only eNB 20 to cause the4G-only eNB 20 to implement this blocking.

As noted above, the 4G-only eNB 20 might normally operate in a firstmode in which the 4G-only eNB 20 allows UEs to be connected with the4G-only eNB 20 regardless of whether the UEs are EN-DC-capable. Thus, inthe first mode, each time a UE connects or seeks to connect with the4G-only eNB 20, the 4G-only eNB 20 may allow the UE to be connected withthe 4G-only eNB without regard to whether the UE is EN-DC-capable.

In response to the detecting of the threshold high extent of occurrencesof EN-DC-capable UEs being connected with the 4G-only eNB 20 when theUEs could instead connect with the EN-DC-capable 4G eNB 14, the 4G-onlyeNB 20 could then transition from operating in the first mode to insteadoperating in a second mode. In the second mode, the 4G-only eNB 20 wouldblock UEs that are EN-DC capable from being connected with the 4G-onlyeNB 20 while still allowing 4G-only UES (i.e., UEs that are notEN-DC-capable) to be connected with the 4G-only eNB 20. Thus, in thesecond mode, each time a UE connects or seeks to connect with the4G-only eNB 20, the 4G-only eNB may block the UE from being connectedwith the 4G-only eNB 20 if the UE is EN-DC capable but would allow theUE to be connected with the 4G-only eNB 20 if the UE is notEN-DC-capable.

The act of the 4G-only eNB 20 blocking EN-DC-capable UEs from beingconnected with the 4G-only eNB 20 while allowing other UE to beconnected with the 4G-only eNB 20 could take various forms.

By way of example, the 4G-only eNB 20 could broadcast a system messagethat is interpretable by EN-DC-capable UEs to prevent the EN-DC capableUEs from seeking to connect with the 4G-only eNB 20 but that is eithernot interpretable by other UEs or that is interpretable by other UEs tonot be applicable to them.

For instance, the 4G-only eNB 20 could broadcast such a message as partof a System Information Block (SIB) or Master Information Block (MIB)that the 4G-only eNB 20 broadcasts and that UEs would read upondiscovering coverage of the 4G-only eNB 20. Thus, if and when anEN-DC-capable UE 34 discovers coverage of the 4G-only eNB 20 and readsthat message, the EN-DC-capable UE would interpret the message to meanthat the UE should not seek to connect with the 4G eNB, and so the UEwould not do so. Whereas, if and when a 4G-only UE 36 discovers coverageof the 4G-only eNB 20 and reads that message, the 4G-only UE maydetermine that the message is not applicable to the 4G-only UE, and sothe 4G-only UE may proceed to connect with the 4G-only eNB 20.

As another example, once a UE connects with the 4G-only eNB 20, the4G-only eNB 20 could then determine whether the UE is EN-DC capable,such as based on capabilities data as noted above, and could disconnectthe UE if the determination is that the UE is EN-DC capable. The 4G-onlyeNB 20 could do this just after the UE connects, or perhaps for a UEthat is already connected with the 4G-only eNB 20 once the blockingstarts. And in the latter case, the 4G-only eNB could wait until such aUE completes any active communication session (e.g., a voice call)before releasing the UE's connection.

Namely, if the 4G-only eNB 20 determines that the UE is EN-DC capable,then, based at least in part on that determination, the 4G-only eNB 20could release the UE's connection and possibly redirect the UE toconnect instead with EN-DC-capable eNB 14. For instance, the 4G-only eNB20 could transmit to the UE an RRC message that indicates release of theUE's RRC connection and perhaps that specifies a carrier and cellidentifier of the EN-DC-capable eNB 14 so that the UE can then insteadscan for and seek to connect with the EN-DC-capable eNB 14. Further, the4G-only eNB could accordingly delete its context record for the UE andtake other action if appropriate to complete release of the UE'sconnection with the 4G-only eNB 20. Whereas, if the 4G-only eNB 20determines that the UE that has connected is not EN-DC-capable, then,based at least in part on that determination, the 4G-only eNB 20 couldretain the connection of that UE.

As still another example, once a UE connects with the 4G-only eNB 20,the 4G-only eNB 20 could then determine whether the UE is EN-DC capable,such as based on capabilities data as noted above, and could hand-outthe UE to a target eNB such as EN-DC-capable 4G eNB 14 for instance. Andas with the disconnecting discussed above, the 4G-only eNB 20 could dothis just after the UE connects, or perhaps for a UE that is alreadyconnected with the 4G-only eNB 20, and in the latter case could waituntil such a UE completes any active communication session (e.g., avoice call) before handing-out the UE.

Namely, if the 4G-only eNB 20 determines that the UE is EN-DC capable,then, based at least in part on that determination, the 4G-only eNB 20could engage in handover signaling over an inter-access-node interface(e.g., an X2) interface with the EN-DC-capable eNB 14 if possible, toprepare the EN-DC-capable eNB 14 to serve the UE, and could thentransmit to the UE a handover directive directing the UE to transitionto be served by the EN-DC-capable eNB 14. Whereas, if the 4G-only eNB 20determines that the UE that has connected is not EN-DC-capable, then,based at least in part on that determination, the 4G-only eNB 20 couldretain the connection of that UE.

As yet another example, if a UE is served by another eNB and might handover to the 4G-only eNB 20, the 4G-only eNB 20 could determine whetherthe UE is EN-DC capable and could control the handover based on thatdetermination. In practice, the 4G-only eNB 20 might learn whether theUE is EN-DC capable by receiving UE capabilities data from the sourceeNB that is currently serving the UE. For instance, the source eNB couldprovide this capabilities data to the 4G-only eNB 20 in an X2-basedhandover request message or the like.

Thus, if the 4G-only eNB 20 determines that the UE that would hand overto the 4G-only eNB 20 is EN-DC capable, then, based at least in part onthat determination, the 4G-only eNB 20 could reject the handover. Forinstance, the 4G-only eNB 20 could respond negatively to thehandover-request message from the source eNB. Whereas, if the 4G-onlyeNB 20 determines that the UE that would hand over to the 4G-only eNB 20is not EN-DC capable, then, based at least in part on thatdetermination, the 4G-only eNB 20 may accept the handover. For instance,the 4G-only eNB 20 could respond positively to the handover-requestmessage from the source eNB.

Other examples could be possible as well.

As further noted above, this blocking of EN-DC-capable UEs from beingconnected with the 4G-only eNB 20 could be done proactively at a giventime of day based on a determination that there tends to be a thresholdhigh extent of occurrences of EN-DC-capable UEs connecting with the4G-only eNB 20 at that time of day. In addition or alternatively, thesystem could discontinue the blocking, such as by transitioning the4G-only eNB 20 back from the second mode to the first mode, in responseto detecting a sufficiently reduced extent of scenarios whereEN-DC-capable UEs seek to connect or connect with the 4G-only eNB 20.

FIG. 2 is a flow chart depicting a method that could be carried out inaccordance with the present disclosure, to control operation of a firstaccess node, where the first access node supports operation according toa first RAT and does not support dual-connectivity operation accordingto the first RAT and a second RAT. For instance, the method couldfunction to control operation of a 4G-only eNB, which supports 4Goperation but does not support EN-DC operation, such as because the 4GeNB is at a cell site where there is no 5G gNB and/or because the 4G eNBis not configured with logic for working to set up EN-DC service or thelike.

As shown in FIG. 2, at block 40, the method includes detecting athreshold high extent of occurrences of dual-connectivity-capable UEsbeing connected with the first access node when thedual-connectivity-capable UEs could instead connect with a second accessnode that supports the dual-connectivity operation. And at block 42, themethod includes, responsive to the detecting, blockingdual-connectivity-capable UEs from being connected with the first accessnode, while allowing UEs that are not dual-connectivity-capable to beconnected with the first access node.

In line with the discussion above, the act of detecting the thresholdhigh extent of occurrences of dual-connectivity-capable UEs beingconnected with the first access node when the dual-connectivity-capableUEs could instead connect with the second access node that supports thedual-connectivity operation could involve determining, respectively foreach occurrence, that a UE is connected with the first access node, thatthe UE is dual-connectivity capable, and that the UE is positioned at alocation where the UE could instead connect with the second access nodethat supports the dual-connectivity operation, and determining that theextent of occurrences is threshold high.

Further, the act of detecting the dual-connectivity-capable UEs beingconnected with the first access node could involve detecting when thedual-connectivity-capable UEs connect with the first access node and/ordetecting that the dual-connectivity-capable UEs have connected or areconnected with the first access node, among other possibilities.

In addition, as discussed above, the act of determining that each suchUE is dual-connectivity capable could be based on capability-data of theUE. And the act of determining that the UE is positioned at the locationwhere the UE could instead connect with the second access node thatsupports the dual-connectivity operation could be based on locationreporting from the UE and/or measurement reporting from the UE (e.g.,the UE reporting to the first access node that the UE is withinsufficiently strong coverage of the second access node).

Further, the act of determining that the extent of occurrences isthreshold high could involve determining that a rate of the occurrencesis at least as high as a predefined threshold rate and/or determiningthat at least a predefined threshold percentage of UEs that connect withthe first access node are dual-connectivity capable.

Still further, as discussed above, the act of blockingdual-connectivity-capable UEs from being connected with the first accessnode while allowing UEs that are not dual-connectivity capable to beconnected with the first access node could involve (i) the first accessnode broadcasting a system message that would causedual-connectivity-capable UEs to not connect with the first access nodebut that would not cause UEs that are not dual-connectivity capable tonot connect with the first access node, (ii) the first access nodereleasing from the first access node a connection with a first UE basedat least on the first UE being dual-connectivity capable but retaining aconnection with a second UE based at least on the second UE not beingdual-connectivity capable, (iii) the first access node handing-out afirst UE based at least on the first UE being dual-connectivity capablebut retaining service of a second UE based at least on the second UE notbeing dual-connectivity capable, and (iv) the first access noderejecting hand-in of a first UE based at least on the first UE beingdual-connectivity capable but accepting hand-in of a second UE based atleast on the second UE not being dual-connectivity capable, among otherpossibilities.

Note that the blocking is thus not blocking generally but is ratherblocking that is specifically keyed to UEs that are dual-connectivitycapable. Further, instances of the blocking could involve a situationwhere a dual-connectivity-capable UE is or gets connected with the firstaccess node and then, to be blocked, gets released, handed-out, or thelike, from the first access node.

In addition, as discussed above, the method could additionally involvepredicting a time of day when the detected threshold high extent ofoccurrences of will occur, such as when the threshold high extent islikely to recur, in which case the act of blockingdual-connectivity-capable UEs from being connected with the first accessnode while allowing UEs that are not dual-connectivity-capable to beconnected with the first access node could involve, based on thepredicting, doing so at or approaching the predicted time of day.

FIG. 3 is another flow chart depicting a method that could be carriedout in accordance with the present disclosure, to control operation of afirst access node, where the first access node supports operationaccording to a first RAT and does not support dual-connectivityoperation according to the first RAT and a second RAT. Here too, themethod could function to control operation of a 4G-only eNB, whichsupports 4G operation but does not support EN-DC operation, such asbecause the 4G eNB is at a cell site where there is no 5G gNB and/orbecause the 4G eNB is not configured with logic for working to set upEN-DC service or the like.

As shown in FIG. 3, at block 44, the method includes detecting athreshold high extent of occurrences of dual-connectivity-capable UEsbeing connected with the first access node when thedual-connectivity-capable UEs could instead connect with a second accessnode that supports the dual-connectivity operation. And at block 46, themethod includes, responsive to the detecting, the first access nodetransitioning from operating in a first mode in which the first accessnode allows UEs to be connected with the first access node regardless ofwhether the UEs are dual-connectivity-capable to instead operating in asecond mode in which the first access node would block UEs from beingconnected with the first access node based on the UEs beingdual-connectivity capable.

FIG. 4 is next a simplified block diagram of an example systemconfigured to control operation of a first access node, where the firstaccess node supports operation according to a first RAT (e.g., 4G LTE)and does not support dual-connectivity operation (e.g., EN-DC) accordingto the first RAT and a second RAT (e.g., 5G NR).

As shown in FIG. 4, the example system comprises at least one processingunit 48 (e.g., one or more general purpose microprocessors and/or one ormore dedicated processors), at least one non-transitory data storage 50(e.g., one or more volatile and/or non-volatile storage components, suchas magnetic, optical or flash storage), and program instructions 52,which could be stored in the non-transitory data storage 50 andexecutable by the processing unit 48 to carry out various operationsdescribed herein. For instance, the operations could include (i)detecting a threshold high extent of occurrences ofdual-connectivity-capable UEs being connected with the first access nodewhen the dual-connectivity-capable UEs could instead connect with asecond access node that supports the dual-connectivity operation and(ii) responsive to the detecting, blocking dual-connectivity-capable UEsfrom being connected with the first access node, while allowing UEs thatare not dual-connectivity-capable to be connected with the first accessnode.

As discussed above, this system could be implemented at the first accessnode, such as by components of the first access node. Alternatively oradditionally, the system could be implemented at an EMS or other entity,in which case, blocking dual-connectivity-capable UEs from beingconnected with the first access node while allowing UEs that are notdual-connectivity-capable to be connected with the first access nodecould involve transmitting to the first access node a directive thatcauses the first access node to operate accordingly, i.e., to which thefirst access node is configured to respond by operating accordingly.

Various features discussed above can be implemented in this context aswell, and vice versa.

For example, the act of detecting the threshold high extent ofoccurrences of dual-connectivity-capable UEs being connected with thefirst access node when the dual-connectivity-capable UEs could insteadconnect with the second access node that supports the dual-connectivityoperation could involve (i) determining, respectively for eachoccurrence, that a UE is connected with the first access node, that theUE is dual-connectivity capable, and that the UE is positioned at alocation where the UE could instead connect with the second access nodethat supports the dual-connectivity operation and (ii) determining thatthe extent of occurrences is threshold high, such as that a rate of theoccurrences is at least as high as a predefined threshold rate.

Further, in terms of blocking dual-connectivity-capable UEs from beingconnected with the first access node while allowing UEs that are notdual-connectivity capable to be connected with the first access node,(i) the first access node be configured to broadcast a system messagethat would cause dual-connectivity-capable UEs to not connect with thefirst access node but that would not cause UEs that are notdual-connectivity capable to not connect with the first access node,(ii) the first access node could be configured to release from the firstaccess node a connection with a first UE based at least on the first UEbeing dual-connectivity capable but to retain a connection with a secondUE based at least on the second UE not being dual-connectivity capable,(iii) the first access node could be configured to hand-out a first UEbased at least on the first UE being dual-connectivity capable but toretain service of a second UE based at least on the second UE not beingdual-connectivity capable, and/or (iv) the first access node could beconfigured to reject hand-in of a first UE based at least on the firstUE being dual-connectivity capable but to accept hand-in of a second UEbased at least on the second UE not being dual-connectivity capable,among other possibilities.

Finally, FIG. 5 is a simplified block diagram of an example first accessnode that may support operation according to a first RAT but not supportdual-connectivity operation according to the first RAT and a second RAT.

As shown in FIG. 5, the example first access node includes a wirelesscommunication interface 54, a backhaul communication interface 56, and acontroller 58, which could be integrated or communicatively linkedtogether by a system bus, network, or other connection mechanism 60and/or could be integrated together or distributed in various ways.

The wireless communication interface 54 could include an antennastructure (e.g., a MIMO antenna array, possibly a massive-MIMO array)62, a transceiver 64, and a power amplifier 66, among one or more otherRF components, to cooperatively facilitate engaging in air interfacecommunication with UEs according to the first RAT. And the backhaulcommunication interface 52 could include a wireless and/or wirelessnetwork communication module configured to support communication withother entities as discussed above.

The controller 58 could then include a processing unit 68 including oneor more processors (e.g., general purpose microprocessors and/ordedicated processing units), non-transitory data storage 70 (e.g., oneor more volatile and/or non-volatile storage components, such asmagnetic, optical or flash storage), and program instructions 72, whichcould be stored in the non-transitory data storage 70 and executable bythe processing unit 68 to cause the first access node to carry outvarious operations described herein. For instance, the operations couldinclude (i) detecting a threshold high extent of occurrences ofdual-connectivity-capable UEs being connected with the first access nodewhen the dual-connectivity-capable UEs could instead connect with asecond access node that supports the dual-connectivity operation and(ii) responsive to the detecting, blocking dual-connectivity-capable UEsfrom being connected with the first access node while allowing UEs thatare not dual-connectivity capable to be connected with the first accessnode.

Various feature described above can be implemented in this context aswell, and vice versa.

Further, the present disclosure contemplates a computer-readable mediumencoded with, storing, or otherwise embodying program instructionsexecutable by at least one processing unit to carry out variousoperations described herein.

Exemplary embodiments have been described above. Those skilled in theart will understand, however, that changes and modifications may be madeto these embodiments without departing from the true scope and spirit ofthe invention.

We claim:
 1. A method for controlling operation of a first access node,wherein the first access node supports operation according to a firstradio access technology (RAT) and does not support dual-connectivityoperation according to the first RAT and a second RAT, the methodcomprising: detecting a threshold high extent of occurrences ofdual-connectivity-capable user equipment devices (UEs) being connectedwith the first access node when the dual-connectivity-capable UEs couldinstead connect with a second access node that supports thedual-connectivity operation; and responsive to the detecting, blockingdual-connectivity-capable UEs from being connected with the first accessnode, while allowing UEs that are not dual-connectivity-capable to beconnected with the first access node, wherein blockingdual-connectivity-capable UEs from being connected with the first accessnode while allowing UEs that are not dual-connectivity capable to beconnected with the first access node comprises at least one operationselected from the group consisting of: (i) broadcasting by the firstaccess node a system message that would cause dual-connectivity-capableUEs to not connect with the first access node but that would not causeUEs that are not dual-connectivity capable to not connect with the firstaccess node, (ii) releasing from the first access node a connection witha first UE based at least on the first UE being dual-connectivitycapable, but retaining by the first access node a connection with asecond UE based at least on the second UE not being dual-connectivitycapable, (iii) handing-out from the first access node a first UE basedat least on the first UE being dual-connectivity capable but retainingby the first access node service of a second UE based at least on thesecond UE not being dual-connectivity capable, and (iv) rejecting by thefirst access node hand-in of a first UE based at least on the first UEbeing dual-connectivity capable but accepting by the first access nodehand-in of a second UE based at least on the second UE not beingdual-connectivity capable.
 2. The method of claim 1, wherein detectingthe threshold high extent of occurrences of dual-connectivity-capableUEs being connected with the first access node when thedual-connectivity-capable UEs could instead connect with the secondaccess node that supports the dual-connectivity operation comprises:determining, respectively for each occurrence, that a UE is connectedwith the first access node, that the UE is dual-connectivity capable,and that the UE is positioned at a location where the UE could insteadconnect with the second access node that supports the dual-connectivityoperation; and determining that the extent of occurrences is thresholdhigh.
 3. The method of claim 2, wherein determining that the UE isdual-connectivity capable is based on capability-data of the UE.
 4. Themethod of claim 2, wherein determining that the UE is positioned at thelocation where the UE could instead connect with the second access nodethat supports the dual-connectivity operation is based on locationreporting from the UE.
 5. The method of claim 2, wherein determiningthat the UE is positioned at the location where the UE could insteadconnect with the second access node that supports the dual-connectivityoperation is based on measurement reporting from the UE.
 6. The methodof claim 2, wherein determining that the extent of occurrences isthreshold high comprises determining that a rate of the occurrences isat least as high as a predefined threshold rate.
 7. The method of claim2, wherein determining that the extent of occurrences is predefinedthreshold high comprises determining that at least a predefinedthreshold percentage of UEs that connect with the first access node aredual-connectivity capable.
 8. The method of claim 1, further comprisingpredicting a time of day when the detected threshold high extent ofoccurrences of will recur, wherein, based on the predicting, theblocking dual-connectivity-capable UEs from being connected with thefirst access node while allowing UEs that are not dual-connectivitycapable to be connected with the first access node is carried out at orapproaching the predicted time of day.
 9. The method of claim 1, whereinthe first RAT is 4G LTE, the second RAT is 5G NR, and thedual-connectivity is EUTRA-NR Dual Connectivity (EN-DC).
 10. A methodfor controlling operation of a first access node, wherein the firstaccess node supports operation according to a first radio accesstechnology (RAT) and does not support dual-connectivity operationaccording to the first RAT and a second RAT, the method comprising:detecting a threshold high extent of occurrences ofdual-connectivity-capable user equipment devices (UEs) being connectedwith the first access node when the dual-connectivity-capable UEs couldinstead connect with a second access node that supports thedual-connectivity operation; and responsive to the detecting,transitioning by the first access node from operating in a first mode inwhich the first access node allows UEs to be connected with the firstaccess node regardless of whether the UEs are dual-connectivity-capableto instead operating in a second mode in which the first access nodewould block UEs from being connected with the first access node based onthe UEs being dual-connectivity capable, wherein blocking UEs from beingconnected with the first access node based on the UEs beingdual-connectivity capable comprises at least one operation selected fromthe group consisting of: (i) broadcasting by the first access node asystem message that would cause dual-connectivity-capable UEs to notconnect with the first access node but that would not cause UEs that arenot dual-connectivity capable to not connect with the first access node,(ii) releasing from the first access node a connection with a first UEbased at least on the first UE being dual-connectivity capable, butretaining by the first access node a connection with a second UE basedat least on the second UE not being dual-connectivity capable, (iii)handing-out from the first access node a first UE based at least on thefirst UE being dual-connectivity capable but retaining by the firstaccess node service of a second UE based at least on the second UE notbeing dual-connectivity capable, and (iv) rejecting by the first accessnode hand-in of a first UE based at least on the first UE beingdual-connectivity capable but accepting by the first access node hand-inof a second UE based at least on the second UE not beingdual-connectivity capable.
 11. The method of claim 10, wherein detectingthe threshold high extent of occurrences of dual-connectivity-capableUEs being connected with the first access node when thedual-connectivity-capable UEs could instead connect with the secondaccess node that supports the dual-connectivity operation comprises:determining, respectively for each occurrence, that a UE is connectedwith the first access node, that the UE is dual-connectivity capable,and that the UE is positioned at a location where the UE could insteadconnect with the second access node that supports the dual-connectivityoperation; and determining that the extent of occurrences is thresholdhigh.
 12. The method of claim 10, wherein the first RAT is 4G LTE, thesecond RAT is 5G NR, and the dual-connectivity is EUTRA-NR DualConnectivity (EN-DC).
 13. A system for controlling operation of a firstaccess node, wherein the first access node supports operation accordingto a first radio access technology (RAT) and does not supportdual-connectivity operation according to the first RAT and a second RAT,the system comprising: a processing unit; non-transitory data storage;and program instructions stored in the non-transitory data storage andexecutable by the processing unit to (i) detect a threshold high extentof occurrences of dual-connectivity-capable user equipment devices (UEs)being connected with the first access node when thedual-connectivity-capable UEs could instead connect with a second accessnode that supports the dual-connectivity operation and (ii) responsiveto the detecting, blocking dual-connectivity-capable UEs from beingconnected with the first access node, while allowing UEs that are notdual-connectivity-capable to be connected with the first access node,wherein blocking dual-connectivity-capable UEs from being connected withthe first access node while allowing UEs that are not dual-connectivitycapable to be connected with the first access node comprises causing thefirst access node to carry out at least one operation selected from thegroup consisting of: (i) broadcasting a system message that would causedual-connectivity-capable UEs to not connect with the first access nodebut that would not cause UEs that are not dual-connectivity capable tonot connect with the first access node, (ii) releasing a connection witha first UE based at least on the first UE being dual-connectivitycapable but retaining a connection with a second UE based at least onthe second UE not being dual-connectivity capable, (iii) handing-out afirst UE based at least on the first UE being dual-connectivity capablebut retaining service of a second UE based at least on the second UE notbeing dual-connectivity capable, and (iv) rejecting hand-in of a firstUE based at least on the first UE being dual-connectivity capable butaccepting hand-in of a second UE based at least on the second UE notbeing dual-connectivity capable.
 14. The system of claim 13, wherein thesystem is implemented at least in part at the first access node.
 15. Thesystem of claim 13, wherein the system is implemented at least in partat an element management system, and wherein blockingdual-connectivity-capable UEs from being connected with the first accessnode while allowing UEs that are not dual-connectivity-capable to beconnected with the first access node comprises transmitting to the firstaccess node a directive that causes the first access node to blockdual-connectivity-capable UEs from being connected with the first accessnode while allowing UEs that are not dual-connectivity-capable to beconnected with the first access node.
 16. The system method of claim 13,wherein detecting the threshold high extent of occurrences ofdual-connectivity-capable UEs being connected with the first access nodewhen the dual-connectivity-capable UEs could instead connect with thesecond access node that supports the dual-connectivity operationcomprises: determining, respectively for each occurrence, that a UE isconnected with the first access node, that the UE is dual-connectivitycapable, and that the UE is positioned at a location where the UE couldinstead connect with the second access node that supports thedual-connectivity operation; and determining that the extent ofoccurrences is threshold high.
 17. The system of claim 16, whereindetermining that the extent of occurrences is threshold high comprisesdetermining that a rate of the occurrences is at least as high as apredefined threshold rate.
 18. The system of claim 13, wherein forblocking dual-connectivity-capable UEs from being connected with thefirst access node while allowing UEs that are notdual-connectivity-capable to be connected with the first access node,the first access node is configured in at least one manner selected fromthe group consisting of: to broadcast a system message that would causedual-connectivity-capable UEs to not connect with the first access nodebut that would not cause UEs that are not dual-connectivity capable tonot connect with the first access node, to release from the first accessnode a connection with a first UE based at least on the first UE beingdual-connectivity capable but to retain a connection with a second UEbased at least on the second UE not being dual-connectivity capable, tohand-out a first UE based at least on the first UE beingdual-connectivity capable but to retain service of a second UE based atleast on the second UE not being dual-connectivity capable, and toreject hand-in of a first UE based at least on the first UE beingdual-connectivity capable but to accept hand-in of a second UE based atleast on the second UE not being dual-connectivity capable, among otherpossibilities.
 19. The system of claim 13, wherein the first RAT is 4GLTE, the second RAT is 5G NR, and the dual-connectivity is EUTRA-NR DualConnectivity (EN-DC).